I'm deciding between 2 mufflers to use as a centre muffler on my r33 as the current centre muffler has collapsed. The choices are round 3" straight through with a 6" body http://www.magnaflow.com/02product/d...rtnumber=14619 (http://www.magnaflow.com/02product/displayapplications.asp?partnumber=14619) oval 3" straight through has a 4" x 9" body http://www.magnaflow.com/02product/d...rtnumber=14319 (http://www.magnaflow.com/02product/displayapplications.asp?partnumber=14319) I want the one that will quiet the exhaust down the most. I know that I should be basing my decision on which ever one has the larger volume but I don't know how to work out the volume of an oval.

The bottom one would be quieter as there is more packing

Mate i work for a exhaust place dont get the 6" round one at the top not enought body size will be to loud go with bottom one

The top one looks like a resonator.

Get the Oval 4"x9" one if you want it to be quiet or just replace it with a straight through pipe if you like to wear your baseball cap backwards...